Boll Weevils, Anthonomus grandis Boheman (Coleoptera: Curculinidae), are insect pests that feed on cotton plants causing serious damage to the plants and reducing harvest yield. Since shortly after the entry of the cotton boll weevil, Anthonomus grandis (Boheman), into the southwestern United States in the early part of this century, baits have been investigated as a control measure for this destructive pest. Previous attempts have been made to trap, kill, or destroy the boll weevil.
Hunter et al (USDA Bur. Entomol. Bull., v. 51, 181 pp., 1905) tested a mixture containing molasses as a feeding stimulant with calcium arsenate. More recently, after the discovery that crude cottonseed contained feeding stimulants and attractants for this species (Daum et al, J. Econ. Entomol., v. 60, 321-325, 1967), cottonseed oil--water emulsion bait formulations were used to infect the insects with a protozoan disease (McLaughlin, J. Invert. Path., v. 9, 70-77, 1967) and to mass-mark field populations (Lloyd et al, J. Econ. Entomol., v. 61, 1440-1444, 1968).
Since the discovery and synthesis of the male boll weevil aggregating pheromone (Tumlinson et al, Science, v. 166, 1010-1012, 1969), the use of baits for controlling the boll weevil has been investigated from time to time, primarily at the Boll Weevil Research Unit at Mississippi State. Most of the baits investigated previously were designed to be applied to the cotton foliage when cotton buds, the natural food for the weevils, were readily available. Competition from the buds as well as application problems and susceptibility to rain wash-off, prevented the baits from being effective enough to be considered a viable control method.
U.S. Pat. No. 3,803,303 describes polymeric compositions for attracting boll weevils using the male sex pheromone, Grandlure, in combination with polyethylene glycol and a toxicant such as p-dichlorobenzene. Additionally, the plant attractants caryophylline oxide and beta-bisabalol were used. The attractant was applied to cotton dental rolls.
U.S. Pat. No. 4,027,420 discloses a bait formulation containing Grandlure absorbed into cigarette filters or cotton dental rolls and containing DDVP (o,o-Dimethyl, 2, 2-dichlorovinyl phosphate). The filters were attached to an airdropped device that was designed to lodge in the foliage cotton plants.
Like all baits for the boll weevil, the approach disclosed in the two patents mentioned above was difficult to evaluate effectively, but did not compare favorably with pheromone baited traps.
The prior art uses of toxic baits have also been in various water-based forms. These bait formulations have been subject to dissolution, dilution, or wash-off by rain. With Grandlure, the application of liquid baits around cotton fields early and late in the season was attempted, likewise with limited success due to the lack of a proper formulation and dispensing system for Grandlure (unpublished).
There is a need for a means to kill chewing insects pests that does not suffer the disadvantages of the prior art insecticide traps or baits described above and that is species specific and thus protecting the insect species that are beneficial to crop plants.